WEBVTT ONE LOCAL MAN TURNED THAT INTO A RATHER UNIQUE BUSINESS, THAT HAVE SOME CALLING HIM THE "BONE FINDER." ♪ ♪ ♪ ♪ >> THEY WILL SEE ME OUT HERE, AND THEY WILL DRIVE IN AND GO, WHAT ARE YOU DOING? SEAN: THIS IS BOB PERRY. BOB: I HAVE BEEN CALLED THE "GRAVE WHISPERER" OR THE "INDIAN JONES OF CEMETERIES." SEAN: HE USES THIS TO FIND UNMARKED BURIALS UNDERNEATH THE GROUND. BOB: THEY ARE PROBABLY BURIED ON TOP OF EACH OTHER. SEAN: IF YOU ARE WONDERING HOW THIS VIETNAM VET ENDED UP DOING THIS, WE DID, TOO. HE USED HIS TECHNICAL DRY BACKGROUND TO DRAW MAPS OF CEMETERIES, BUT HE REALIZED THAT MANY BURIAL SITES WERE NOT IN THE RECORDS, SO WE THOUGHT -- BOB: I THOUGHT I WOULD FIND SOME ADDITIONAL EQUIPMENT TO SCAN FOR BURIALS, AND IT IS CALLED GROUND PENETRATING RADAR. ♪ ♪ ♪ ♪ ♪ SEAN: USING SIMILAR TECHNOLOGY, GPR OR GROUND PENETRATING RADAR BOUNCES SIGNALS ON OBJECTS IN THE GROUND, AND THIS SCREEN WILL SHOW THEM, IT 10, 20, -- WILL SHOW THEM, 10, 20, EVEN 30 FEET HELLO THE GROUND. THE RECORD-KEEPING IS OFTEN WRONG. >> THEY THINK THE LOT IS OPEN, AND THEY GO AND PUT SOMEBODY IN THE GROUND AND FIND OUT SOMEBODY ELSE IS ALREADY BURIED THERE. SEAN: ROBERT WILL DO A GRID SEARCH IN THE CEMETERIES, AND THE LITTLE, UPSIDE DOWN U SHAPE IS A HIT, BUT IT COULD BE OTHER THINGS. >> IT COULD BE ROOTS RUNNING IN THE GROUND. SEAN: EXPERIENCE ALLOWS HIM TO DECIPHER ROCKS AND POSSIBLE BURIAL SITES. >> I WILL CALL IT A HYPER BURIAL -- CALL IT A HIGH OF ABILITY. -- A HIGH PROBABILITY. YOU DO NOT KNOW UNTIL YOU DIG DOWN. SEAN THAT DEVICE ROBERT RELIES ON, IT TURNS OUT IT WAS MADE A FEW MILES AWAY IN NASHUA, AT A COMPANY THAT DOES NOT LET SOLID EARTH STOP THEM. >> IT IS MAKING THE INVISIBLE VISIBLE. SEAN: HE HEADS UP GSSI, OR GEOPHYSICAL SURVEY SYSTEMS, INC., CREATED BY ENGINEERS IN THE 1970'S WHO -- CHRIS: IT SENDS RADIO WAVES INTO THE EARTH AND LOOKS AT THE REFLECTIONS TO GATHER INFORMATION. SEAN: THE SIMPLE DEVICES HAVE EVOLVED OVER THE YEARS INTO PORTABLE, LIGHT, AND POWERFUL RADAR DEVICES THAT ARE BEING USED ALL OVER THE WORLD. WHAT OF THE MOST COMMON USES, LOOKING INSIDE CONCRETE IN CONSTRUCTION SITES TO FIND -- ONE OF THE MOST COMMON USES, LOOKING INSIDE CONCRETE IN CONSTRUCTION SITES TO FIND FLAWS. >> HE WENT TO KNOW BEFORE YOU PUT IN THE SHOVEL OR THE -- YOU WANT TO KNOW BEFORE YOU PUT IN THE BACKHOE OR SHOVEL. SEAN: PETER IS THE ARCHAEOLOGICAL SPECIALIST FOR GSSI. HE SAYS USING MULTIPLE SCANS FROM ABOVE, THEY CAN CREATE 3-D IMAGES OF WHAT IS UNDERNEATH THE GROUND AT A POTENTIAL HISTORICAL SITE. >> AND THEN WE CAN SLICE DOWN THROUGH IT, JUST LIKE WE WERE USING A BACKHOE, AND LOOK AT WHERE OF -- ALL OF THE THINGS WERE, ALL WITHOUT USING A SHOVEL. SEAN: IN FACT, GSSI HAS BEEN USED TO FIND THINGS LIKE DINOSAURS AND PEOPLE. THEIR LATEST WRITER IS DESIGNED TO FIND SURVIVORS -- THEIR LATEST ITEM IS DESIGNED TO FIND SURVIVORS. >> WE CAN DETECT THROUGH MANY LAYERS OF CONCRETE TO SEE IF THERE IS ANYBODY BREATHING, STILL LIVING, UNDERNEATH. SEAN: BUT ROBERT USES HIS GSSI DEVICE TO FIND THE DEAD. IN FAT, HE JOINED FORCES WITH HIS SON -- IN FACT, HE JOINED FORCES WITH HIS SON TO KEEP UP. MODERN MAPPING, USING A ROBOTIC SURVEY TOOL. JESSE: THEY WANT MORE MODERN MAPS AND SOMETHING THEY CAN HAVE ON THEIR COMPUTERS. SEAN: THE COMPANY GOES AROUND THE COUNTRY, EVEN FINDING PREVIOUS MASS BURIALS, AND EVEN A GHOSTLY IMAGE. ♪ SEAN: BUT HIS MOST INTERESTING FIND CAME WHILE DOING A D IN MANCHESTER IN 2010, LOOKING FOR POSSIBLE GRAVES. IT PROMPTED A CALL TO POLICE. >> I CAME ACROSS A WORLD WAR II HAND GRENADE. SEAN: HE THOUGHT IT WAS FAKE, BUT JUST IN CASE, THE BOMB SQUAD WAS CALLED IN. >> I WAS TOLD LATER ON IT WAS STILL ACTIVE. SEAN: EVEN THOUGH HE IS KNOWN AS THE "BONE FIND," THANKS TO MODERN TECHNOLOGY, WHAT IS HIDDEN IS NO LONGER HIDDEN FROM SEEING EYES. ♪